Hi Joanna,
I can't answer the question of how much is too much. I would definitely say it is different for everyone depending on thier weight, height, how much food is in their system, etc. The smartest and safest way to take your medication is to take it exactly as your doctor perscribes it. This will insure that you do not take more than you're suppose to. If you feel as if the drug is not working for you like it used to, it would be best to tell your doctor so he could discuss safe alternatives with you.